This invention relates generally to a system for supplying power to both a pressure-operated utilization device and an electrically operated utilization device.
While the system of the invention is susceptible to many applications, it is particularly useful in connection with mobile man lifts or access platforms. By way of example, a mobile man lift may comprise a self-propelled vehicle having a platform thereon for supporting a worker. The platform is adapted to be raised and lowered by a hydraulic actuator so as to enable the worker to perform tasks at various elevations. Among those tasks may be jobs performed with an electrically operable utilization device such as a tool and particularly a tool adapted for operation from a 115 or 230 volt source of alternating current (a.c.) voltage.
In most commercially available man lifts, there is no a.c. voltage source available on the platform for operating the tool. As a result, it is necessary for the worker to string a long power cord downwardly from the platform to a fixed power outlet located near ground level either inside or outside of a building. Such a cord limits travel of the vehicle and also is cumbersome when the lift is raised and lowered. In addition, it sometimes is necessary to unplug the cord from one outlet and to plug the cord into a different outlet on a frequent basis. Thus, the use of a long power cord makes it more difficult and time-consuming for the worker to perform the tasks at hand.
The platform usually is raised and lowered by a reciprocating hydraulic actuator. The mobile man lift usually includes other reciprocating hydraulic actuators and/or rotary hydraulic actuators for various purposes such as steering, leveling and the like. The hydraulic actuators are adapted to be pressurized by a rotary pump (e.g., a gear pump) associated with a hydraulic reservoir on the vehicle. The pump may be driven either by the main engine or motor of the vehicle or by an auxiliary motor.